Inheritance question & advice.

My fathers passed away 5 years back. he was survived by 4 sons, wife, daughter and his mother. My grandmother has property of her own and is survived by 4 daughters & sons/daughters of 2 sons (including my fathers). My fathers brother passed away this year and a few of my aunts are pressuring my grandmother to register off property under her name to them. they have decided that what my grandmother inherited from my father will be passed on to us (4 sons + 1 daugher) and what she inherits from my uncle to his children(2 sons+ 1 daughter). she had already registered her share from my fathers estate (excluding house) to us children when my fathers brother was alive. (we were not legal heirs at that time). she is saying that she will register her share in the house to us such that it will come in effect only after her passing. my question is this. will such a document hold up in court. can it be challenged by other heirs ( fathers sisters etc..) also note that we have not partitioned our fathers estate because of some pending commitments, osiyath etc..